Watermarking of audio signals intends to manipulate the audio signal in a way that the changes in the audio content cannot be recognized by the human auditory system. Many audio watermarking technologies add to the original audio signal a spread spectrum signal covering the whole frequency spectrum of the audio signal, or insert into the original audio signal one or more carriers which are modulated with a spread spectrum signal. At decoder or receiving side, in most cases the embedded reference symbols and thereby the watermark signal bits are detected using correlation with one or more reference bit sequences. For audio signals which include noise and/or echoes, e.g. acoustically received audio signals, it may be difficult to retrieve and decode the watermark signals at decoder side in a reliable way. For example, in EP 1764780 A1, U.S. Pat. No. 6,584,138 B1 and U.S. Pat. No. 6,061,793 the detection of watermark signals using correlation is described. In EP 1764780 A1, the phase of the audio signal is manipulated within the frequency domain by the phase of a reference phase sequence, followed by transform into time domain. The allowable amplitude of the phase changes in the frequency domain is controlled according to psycho-acoustic principles.